1. Field of the Invention
The present invention generally relates to radio frequency identification (RFID) tags, and more particularly to secure negotiation of a population of RFID tags.
2. Background Art
In an RFID system, an RFID reader interrogates one or more RFID tags for information. The RFID reader may be required to distinguish between and communicate with a large number of different RFID tags within a given communication range. Typically, a unique identification number identifies each tag. It is important that the RFID reader is capable of quickly and accurately reading the identification (ID) number associated with each tag. In order to interrogate a particular tag, typically, the reader broadcasts the identification number of the tag, in a bit-by-bit fashion, and the tag responds.
However, such RFID systems can suffer from security problems. In a first security problem, a signal transmitted from the reader to a tag may travel a long distance, such as a distance of miles. Thus, when the reader broadcasts a complete tag ID number, an undesired third party can receive this broadcast, and collect this transmitted data. Thus, an undesired third party can obtain the identification number of the tag in this manner.
In a second security problem, an undesired third party can fool or “spoof” an RFID reader into broadcasting the identification number of a tag in order to collect it. For example, in such a situation, the undesired third party responds to broadcasts of a reader. The undesired third party transmits false tag responses to the reader to cause bit collisions that thereby cause the reader to broadcast the identification number bits.
Thus, what is needed is a way of communicating with tags on an open-air communication channel, while protecting tag data, such as the tag identification number.